Quantifying the occurrence, distribution and contribution of Swedish maerl bedsUnderexplored Reefs

Lina Rasmusson¹, Mackenzie Doulton¹, Jason Hall-Spencer^{2, 3}, Thomas Staveley⁴, Emily Stragapede¹

¹University of Gothenburg, Sweden - ²University of Plymouth, U.K - ³University of Tsukuba, Japan - ⁴Swedish University of Agricultural Sciences, Sweden

Maerl beds are biogenic reefs consisting of both alive and dead free-living coralline algae with high ecological value. These algal deposits have an extensive, yet declining, distribution in many coastal areas around the world, however, known locations in Sweden are sparse. Limited information regarding maerl in Sweden is a knowledge gap that hinders the implementation of marine management plans. The Swedish Agency for Marine and Water Management has listed maerl beds in their statutory regulations as a marine habitat that should be increased and not decline. However, how can one protect and restore, if the habitat of interest has not been surveyed and is unreported?
This project will put Swedish maerl beds on the map, literally. By combining historical sightings and citizen science, together with up-to-date geographic information and environmental information, to build a distribution model used for ground truthing in the field. Despite scarce reports so far, two offshore banks in Kattegat (an arm of the Atlantic Ocean) have been found that are Swedish maerl bed strongholds. These will be used as focal areas to assess biodiversity linked ecosystem services and will be investigated using eDNA for identification of macroalgae, invertebrates, and bony and cartilaginous fish, together with grab samples for epibenthos and infauna determination. Moreover, annual budgets for carbonate production and CO2 removal will be calculated using laboratory assessments of photosynthesis, respiration and calcification.
This project will help deliver vital knowledge of maerl beds that is needed for Sweden to achieve marine management and conservation goals.